1. Field of the Invention
This invention relates to improvements in a modified Tessar type behind stop lens used in a compact camera or the like and having an angle of view of 60.degree. or more and brightness of the order of F3.5.
2. Description of the Prior Art
As a behind stop lens used in a compact camera and having an angle of view of 60.degree. or more and brightness of the order of F3.5, there is known a Tessar type lens and a modified Tessar type lens in which the direction of the cemented surface of a cemented lens which is a third group has been changed. Since, however, the stop is positioned rearwardly of the lens, the principal light ray of the oblique light flux passing through the center of the stop passes through a position very far from the optical axis in the neighborhood of the first lens group which is most adjacent to the object side, and this leads to a structure in which various aberrations are liable to occur. Due, due to the fact that the lower light flux relative to the principal light ray of the oblique light flux passes through a point relatively near the center of the stop, it performs an especially important role in the imaging performance of the photographic lens. Nevertheless, the lower light flux relative to the principal light ray passes through the marginal portion of the forward lens and therefore, substantial coma, chromatic aberration of coma and astigmatism have occurred, and it has been difficult to reduce these aberrations sufficiently at the same time.